Method for making insulated wire and product obtained thereby



METHOD FOR MAKING INSULATED WIRE AND PRODUCT OBTAINED THBRBBY Filed Oct19 1925 Patented 16, 1932 UNIT D STATES PATENT OFFICE THOMAS V. BINIOBE,OF LONG ISLAND CITY, NEW YORK, AND HAIBOLD DE BLO IB RICE, OF BRISTOL,RHODE ISLAND, ASSIGNORS TO NATIONAL INDIA RUBBER, COMPANY, OF

BRISTOL, RHODE ISLAND, a

CORPORATION 01' BHODE ISLAND METHOD FOR MAKING INSULATED WIRE ANDPRODUCT OBTAINED THEBEBY Application and mm is, me Serial 80. 142,711. a

This invention relates to the manufacture of rubber insulated wire andparticularly to theinsulation oi." wire with a, pre-vulcanized rubbercompound.

According to the present practice,: electric' conductorsare insulatedwith rubber com positions which are applied, in the case of the smallerflexible. wires cord, telephone wire, fixture wire, etc., over a servinga placed on-the bare copper,

the size of the latter. The rubber insulation is always applied in theform of an'un vulcanized composition and theapplication is carried outeither by extruding the rubber com osition directly around the conductorafter it has been wound. with yarn or plated with tin, or the rubberisapphedin a strip wrapped around the conductor. In

go either instance,it is customary to subseinently vulcanize the rubbercompound. his operation requires several cumbersome steps. When therubber composition is applied by the tubing method, the coated wire,

as as it comes from the tubin machine, is

coiled in a pan and dusted with talc, the operation being known. aspanning. These 7 pans holdin under 10,000 feet of wire, and usuailylesshan 6,500 feet, are transported so bodily into a vulcanizer. Afterzatio'n the wire is removed from the the vulcanipan and cleansed of thetalc, this operation being known as unpannmg or dep The talc orsoapstone treatment, as well as the method of receiving the wire afterthe tubin operation, are employed to obviate any di cult resulting fromthe sticky nature of unvulcanized rubber du the manufacturingoperations. Another ifliculty which is eliminated by, panni is thatcaused by pressure. This rooedureis therefore almost universally empoyed before the rubber in sulated Vgle cafn h f a e n in urt er manuactu roces s as sh ich as braiding, twisting, e sII i the so-calledstrippin 'quently employed or larger sizes of conductors, the wire maybe taken up on reels prior known as lamp of yarn or over a plating oftin. depending upon (luctors.

method for makin objects will comprisinlg applying a vulcanizedinsulating the tendency towards de ormation of the unvulcanized rubbercomposition under slight be wound on reels for stor-e method, which isfre-.

neither of these ma be considered standard practice. In genera ,thestripping method is much cleaner than the tubing method, for it is notthe practice to resort to panning and unfi'anning in the strippingmethod. There is,

owever, a serious disadvantage in the strippin method-that it is wellnigh im ossible to o tain a uniform wall thickness 0 insulation, andparticularly on the, smaller con- The primary object of the presentinven-' tion isto furnish a method for insulating wire with a rubbercompound which is not deformable at ordinary temperature, does not"require vulcanization and is therefore free from the'necessity ofanning and unpanning. Another object o the invention is to provide asimple, rapid and inexpensive method of applying a vulcanized rubbercompound to a metallic conductor or conductors. A further object is toprovide a insulated wire in conousands of feet. Other I apparent fromthe description 5 tinuous len ths of 7 and claims.

The invention maybe briefly described as com can to a metallic conductoreither soli braided, or stranded, and subsequently applyingjackets,coatings, and other wrappage when desired. 7 In Fig. 1 of the drawing isillustrated one ,manner in which a vulcanized rubber comgound may beapplied to a metallic eonuctor and the covered conductor reeled pre- W yto p y g thereto.

Fig. 2 is a diagrammatic illustration of fiductor may be first coveredwith a fibrous covering how a co vulcanized rubber compound andsubsequently wrapped with a fibrous covering.

its one illustration of a suitablecompound, vulcanized rubber is mixedwith an equal weight of asphalt b softenin the asphalt on a mixing millan addin tfievulcanized rubber to t e asphalt after I e latter has be acome a continuous layer on the mixing roll.

Mixing is continued until the vulcanized rubber has substantialldisappeared from view. What actually appens is that the vulcanizedrubber is reduced to very small coherent particles, and becomessubstantially invisible as vulcanized rubber. To this mix ture is added7 of a wax such as Montan wax. The plasticity and other phys1calproperties of this composition at ordinary temperatures greatly resemblethose of heatsoftened hard rubber. The composition is capable of settingrapidly to this physical condition upon cooling.

The above described vulcanized rubberasphalt-wax composition may beplasticized on a mill to a sufficient degree to emit its beingsatisfactorily handled in t e tubing machines used in insulationpractice. The invention may be in part carried out by simply extrudingthis heated composition on to the wire, as illustrated in Fig. 1whereina wire 1 from roll 2 is passed through an extruder 3. Inasmuch asthe composition has a certain degree of ri 'dity when cool, is notsticky, and resist deiformation, the covered wire may be directly woundupon a reel 4. At this stage of manufacture, the invention has furnis eda wire covered with a vulcanized rubber com osition, whichdoes notrequire any further ieat treatment. One of the advantages of the presentinvention here becomes apparent. According to the improved proces thecumbersome and expensive operations of panning, vulcanizing andunpanning are completely eliminated. The com ition it self is quiteinexpensive. Vulcanized mbber of high quality does not cost as much asmost of the cheaper reclaims, andcertainlyismuch less expensive thancrude rubber. The asphalts are likewise inexpensive. Due to the propertyof the improved composition of maintaining its shape when cool, it ma bereadil seen that another advantage has n in the preclusion offlattening, which so often takes place with unvulcanized rubcomposition.The Montan wax serves as a lubricant, but is not an essential ingredientof the composition. It may be replaced if desired with other waxes orsofteners.

Inasmuch as the com tion used herein is prevulcanized, there s at nostage of the process any risk of scorching the insulation compound,whereas this risk is always present even with low-grade insulationcontaining unvulcanized rubber and is. articularly hazardous where thevulcanizah e insulation contains organic accelerators. Anotherdisadvantage which is'overcome is that of blistering duringvulcanization; since the material of the present invention is vulcanizedbefore it is ap lied to the wire, no blistering canbe caused y anymoisture in the cotton or cop r and as a result there will be pro rubasvaase be loosened from the wire. A particularly outstanding advantageof the present invention is that rubber-insulated conductors may be madein any desired length. For example, miles of wire may be made in acontinuous length. The advantage derived here is not only 'in theabsence of splicing but is also in the subsequent steps of braiding andwrapping. There is no time lost for splicing in braiding machines, anddue to the fact that the length of wire is so great, a given number ofbraiding machines will require much less attention on the partof theoperator, thereby accomplishing a saving in labor cost. The economyeffected by the manufacture of long lengths of wire will also benoticeable during the commercial use of the wire, for splicings may beconsiderably reduced in number. Another advantags is that there are nomigratory ingredicnts in the vulcanized insulation composition and thereis no resulting action between the conductor and the ingredients, withthe attendant reduction of insulating strength 7 and increasedshort-circuit hazard.

Although in general, braiding machines do not operate as fast as tubinmachines, it is possible, insofar as the insu ating composition isconcerned, to run the wire after the tubing operation directly throughthe braider, thus giving a continuous o eration. Thus, as indicated inFig. 2 wire 1 rom roll 5 may be passed through an extruder 8 and througha cooling atmosphere directly into a braiding machine 7 after which itmay be wound upon a reel 8. -However, since no deformation results fromreeling u the improved insulated wire directly a r application of therubber compound, the covered wire may be wound on reels and when convenient, braided or wrapped with yarn or tape or pa r, or finished inany desired manner. 'des eliminating the cost of panning, vulcanizingand unpanning, no

small benefit is gained by the elimination of the tale dust nuisance andits discomfort to the workman.

The vulcanized rubber com ition herein described has a high electricalinsulation value, and in addition is characterized by its unusualresistance to aging, whether oxyn, ozone, heat or ultra-violet light. Int is respect the product more nearly resembles hard rubber. While in theabove illustration a compoundhasbeen given as comprisin equal parts ofvulcanized rubber and asph t, it is of course understood that thesepgrtions may be changed, more or less i313 ingredients and othermaterials which d to the properties'of the composition, but

which do not require vulmnization; It is compcsinot the intentiontofinclude in the r being used. It is also within the scope of theinvention to employ compoundno ten ency of the improved insulation totion any unvulcanind rubber.

amaze 3 While in the above the vulcanized rubberasphalt-Montan waxcomposition has been described as an insulator to be applied directlyover the bare wire, the composition may 5 also be used as anintermediate covering or as an outer covering over one or more suitablyinsulated conductors, and the same method of application may beemployed.

, Braided or wrapped coverings may be applied as necessary, and thesemay be flameresistant (asbestos, etc.) or fireroofed, water-proofed andweather-proofe The composition employed in this invention furnishes alow cost, high grade, vulcanized in- 5 sulation or covering which can bea plied with a tubing machine. The covered wire may be wrapped directlyupon a reel placed behind the tubing machine, just far enough away fromthe tuber so that the composition has an opportunity to cool, which willtake place in a few feet of travel.

Having thus described our invention, what we claim as new and useful anddesire to secure by Letters Patents is:

1. An improved method for making insulated wire which comprises coverina metallic conductor with a single layer 0 homogeneous warm plasticinsulatin composition containing prevulcan'ized ,ru ber, cooling andimmediately applying protective material over the rubber insulation andfinishing the insulated wire without vulcanization.

2. An improved method for making insulated wire which comprisesextruding an insulating compound comprising vulcanized rubber andbituminous material over a metallic conductor, cooling, and immediatelyapplying protective material over the rubber insulation and finishingthe insulated wire 40 without vulcanization.

3. An improved method for making insulated wire which comprisesextruding an insulating compound comprising vulcanized rubber andbituminous material over a. me-

tallic conductor, cooling, winding up the insulated wire upon a reel,and subsequently applying thereto fibrous covering over the insulationand finishing the insulated wire without vulcanization. 1 4. An improvedmethod for making insulated wire which comprises extruding an'insulatingcompound comprising vulcanized rubber and bituminous material over ametallic conductor, cooling, winding up'the insulated wire upon a reel,and subsequently braiding a jacket over the insulation and finishing theinsulated wire without vulcanization.

Signed at New York, New York, this 8th day of October, 1926.

THOMAS V. BINMORE. Signed at New York, New York, this 8th day ofOctober, 1926. HAROLD DE BLOIS RICE.

